U.S. patent application number 11/213307 was filed with the patent office on 2006-02-02 for footwear sole component with an insert.
This patent application is currently assigned to NIKE, Inc.. Invention is credited to Bruce J. Kilgore, John F. Swigart.
Application Number | 20060021251 11/213307 |
Document ID | / |
Family ID | 37460349 |
Filed Date | 2006-02-02 |
United States Patent
Application |
20060021251 |
Kind Code |
A1 |
Swigart; John F. ; et
al. |
February 2, 2006 |
Footwear sole component with an insert
Abstract
A sole component for footwear combining the desirable response
characteristics of a fluid filled chamber and an elastomeric
material is disclosed. The chamber can be formed as a single
bladder chamber in contact with an elastomeric midsole or as a
single chamber by a sealing a void in elastomeric material.
Alternately, an insert having the shape of the bladder, and
potentially formed from foam, may be positioned within the chamber.
The interface between the chamber and elastomeric material is
sloped and gradual so that the shape of the chamber and its
placement in a midsole determine the combination of response
characteristics in the sole component. The chamber has a relatively
simple shape with one axis of symmetry with a rounded portion and a
narrow portion.
Inventors: |
Swigart; John F.; (Portland,
OR) ; Kilgore; Bruce J.; (Lake Oswego, OR) |
Correspondence
Address: |
BANNER & WITCOFF, LTD.
1001 G STREET, N.W.
WASHINGTON
DC
20001-4597
US
|
Assignee: |
NIKE, Inc.
Beaverton
OR
|
Family ID: |
37460349 |
Appl. No.: |
11/213307 |
Filed: |
August 26, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10845302 |
May 14, 2004 |
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11213307 |
Aug 26, 2005 |
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10143745 |
May 9, 2002 |
6796056 |
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10845302 |
May 14, 2004 |
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Current U.S.
Class: |
36/29 ;
36/28 |
Current CPC
Class: |
A43B 13/20 20130101;
A43B 7/144 20130101; A43B 7/145 20130101; A43B 7/1425 20130101;
A43B 3/0031 20130101; A43B 13/186 20130101; A43B 13/189 20130101;
A43B 13/187 20130101; A43B 13/188 20130101 |
Class at
Publication: |
036/029 ;
036/028 |
International
Class: |
A43B 13/18 20060101
A43B013/18; A43B 13/20 20060101 A43B013/20 |
Claims
1. An article of footwear comprising a sole that defines a void, at
least one insert being at least partially positioned within the
void, the insert having a first surface, an opposite second
surface, and a sidewall surface extending between a perimeter of
the first surface and a perimeter of the second surface, the first
surface having a pair of rounded end areas, one of the rounded end
areas being larger than another of the rounded end areas, and the
first surface having a greater area then the second surface such
that the sidewall surface tapers between the first surface and the
second surface.
2. The footwear recited in claim 1, wherein a portion of the sole
that defines the void is formed from a first foam material and the
insert is formed from a second foam material.
3. The footwear recited in claim 2, wherein the first foam material
is less compressible than the second foam material.
4. The footwear recited in claim 1, wherein the void is a
depression in an upper surface of a midsole of the footwear, and
the first surface of the insert is positioned at an elevation of
the upper surface.
5. The footwear recited in claim 1, wherein the void is a
depression in a lower surface of a midsole of the footwear, and the
first surface of the insert is positioned at an elevation of the
lower surface.
6. The footwear recited in claim 1, wherein a substantial portion
of the first surface and a substantial portion of the second
surface are planar.
7. The footwear recited in claim 6, wherein the substantial portion
of the first surface is substantially parallel to the substantial
portion of the second surface.
8. The footwear recited in claim 1, wherein the void is a
depression in a removable sockliner of the footwear.
9. The footwear recited in claim 1, wherein the insert is
positioned in a heel region of the footwear and at a position that
corresponds with a calcaneus of a foot.
10. The footwear recited in claim 1, wherein the at least one
insert is three inserts distributed in a heel region and a forefoot
region of the footwear.
11. The footwear recited in claim 1, wherein the insert is
positioned to correspond with a joint between phalanges and
metatarsals of the foot.
12. The footwear recited in claim 1, wherein the at least one
insert is a first insert and a second insert, the first insert
being oriented in a medial-lateral direction and positioned to
correspond with a joint between phalanges and metatarsals of the
foot, and the second insert is positioned forward of the first
insert and oriented in a direction of a longitudinal length of the
midsole.
13. The footwear recited in claim 1, wherein a cover sheet is
secured to the sole and extends over the insert.
14. The footwear recited in claim 13, wherein the cover sheet
contacts one of the first surface and the second surface of the
insert.
15. An article of footwear having a sole that includes at least one
insert at least partially encapsulated within the sole, the insert
comprising: a first surface having a first perimeter with a pear
shape, at least a portion of the first surface being substantially
planar; a second surface spaced from the first surface, the second
surface having a second perimeter with a pear shape, at least a
portion of the second surface being substantially planar, and the
second surface having a lesser area than the first surface; and a
sidewall surface extending between the first perimeter and the
second perimeter, the sidewall surface tapering inward between the
first surface and the second surface, wherein a portion of the sole
adjacent to the insert is formed from a first foam material and the
insert is formed from a second foam material.
16. The footwear recited in claim 15, wherein the first foam
material is less compressible than the second foam material.
17. The footwear recited in claim 15, wherein the sole defines a
void that receives the insert.
18. The footwear recited in claim 17, wherein the void is a
depression in an upper surface of a midsole portion of the sole,
and the first surface of the insert is positioned at an elevation
of the upper surface.
19. The footwear recited in claim 15, wherein the void is a
depression in a lower surface of a midsole portion of the sole, and
the first surface of the insert is positioned at an elevation of
the lower surface.
20. The footwear recited in claim 15, wherein a substantial portion
of the first surface and a substantial portion of the second
surface are planar.
21. The footwear recited in claim 20, wherein the substantial
portion of the first surface is substantially parallel to the
substantial portion of the second surface.
22. The footwear recited in claim 15, wherein the first surface has
a pair of rounded end areas, and one of the rounded end areas of
the first surface is larger than another of the rounded end areas
of the first surface.
23. The footwear recited in claim 15, wherein the insert is
positioned in a removable sockliner of the footwear.
24. The footwear recited in claim 15, wherein the insert is
positioned in a heel region of the footwear and at a position that
corresponds with a calcaneus of a foot.
25. The footwear recited in claim 15, wherein the insert is
positioned to correspond with a joint between phalanges and
metatarsals of the foot.
26. The footwear recited in claim 15, wherein the at least one
insert is a first insert and a second insert, the first insert
being oriented in a medial-lateral direction and positioned to
correspond with a joint between phalanges and metatarsals of the
foot, and the second insert is positioned forward of the first
insert and oriented in a direction of a longitudinal length of the
midsole.
27. The footwear recited in claim 15, wherein a cover sheet is
secured to the midsole and extends over the insert.
28. The footwear recited in claim 27, wherein the cover sheet
contacts one of the first surface and the second surface of the
insert.
29. An article of footwear having a midsole and at least one insert
at least partially encapsulated within the midsole, the insert
comprising: a first surface with a first perimeter extending around
the first surface, the first perimeter having a pair of rounded end
areas, one of the rounded end areas being larger than another of
the rounded end areas, the first surface being symmetrical about an
axis extending between the rounded end areas and otherwise
asymmetrical; a second surface spaced from the first surface, the
second surface having a second perimeter extending around the
second surface, and the second surface having a lesser area than
the first surface; and a sidewall surface extending between the
first perimeter and the second perimeter of the second surface, the
sidewall surface tapering inward between the first surface and the
second surface, wherein a portion of the midsole adjacent to the
insert is formed from a first foam material and the insert is
formed from a second foam material, the first foam material being
less compressible than the second foam material.
30. The footwear recited in claim 29, wherein the insert is
embedded within an upper surface of the midsole, and the first
surface of the insert is positioned at an elevation of the upper
surface.
31. The footwear recited in claim 29, wherein the insert is
embedded within a lower surface of the midsole, and the first
surface of the insert is positioned at an elevation of the lower
surface.
32. The footwear recited in claim 29, wherein the insert is
positioned in a heel region of the footwear and at a position that
corresponds with a calcaneus of a foot.
33. The footwear recited in claim 29, wherein the insert is
positioned to correspond with a joint between phalanges and
metatarsals of the foot.
34. The footwear recited in claim 29, wherein the at least one
insert is a first insert and a second insert, the first insert
being oriented in a medial-lateral direction and positioned to
correspond with a joint between phalanges and metatarsals of the
foot, and the second insert is positioned forward of the first
insert and oriented in a direction of a longitudinal length of the
midsole.
35. The footwear recited in claim 29, wherein a cover sheet is
secured to the midsole and extends over the insert.
36. An article of footwear having a sole component comprising: a
midsole formed from a first foam material, the midsole having an
upper surface and an opposite lower surface, and the midsole
defining a void; an insert formed from a second foam material that
is less compressible than the first foam material, the insert being
at least partially positioned within the void, and the insert
having a first surface, an opposite second surface, and a sidewall
surface extending between a perimeter of the first surface and a
perimeter of the second surface, the first surface having a greater
area then the second surface such that the sidewall surface tapers
between the first surface and the second surface; and a cover sheet
secured to the midsole and extending over the insert, the cover
sheet contacting one of the first surface and the second surface of
the insert.
37. The footwear recited in claim 36, wherein the void forms a
depression in the midsole, and the first surface of the insert is
positioned at an elevation of the upper surface of the midsole.
38. The footwear recited in claim 36, wherein the void forms a
depression in the midsole, and the depression has a shape that
corresponds with the second surface and the sidewall surface.
39. The footwear recited in claim 36, wherein a substantial portion
of the first surface and a substantial portion of the second
surface are planar.
40. The footwear recited in claim 39, wherein the substantial
portion of the first surface is substantially parallel to the
substantial portion of the second surface.
41. The footwear recited in claim 36, wherein the first surface has
a pair of rounded end areas, one of the rounded end areas being
larger than another of the rounded end areas.
42. The footwear recited in claim 41, wherein the first surface is
symmetrical about an axis extending between the rounded end areas
and otherwise asymmetrical
43. The footwear recited in claim 36, wherein at least one of the
first surface and the second surface have a pear shape.
44. The footwear recited in claim 36, wherein a portion of the
first surface is substantially parallel to a portion of the second
surface.
45. An article of footwear comprising a sole that defines a first
void and a second void, a first insert being at least partially
positioned within the first void, and a second insert being at
least partially positioned within the second void, each of the
inserts having a first surface, an opposite second surface, and a
sidewall surface extending between a perimeter of the first surface
and a perimeter of the second surface, the first surface having a
pair of rounded end areas, one of the rounded end areas being
larger than another of the rounded end areas, and the first surface
having a greater area then the second surface such that the
sidewall surface tapers between the first surface and the second
surface, the first insert being oriented in a medial-lateral
direction and positioned to correspond with a joint between
phalanges and metatarsals of the foot, and the second insert is
positioned forward of the first insert and oriented in a direction
of a longitudinal length of the midsole.
46. The footwear recited in claim 45, wherein a portion of the sole
that defines the void is less compressible than the inserts.
47. The footwear recited in claim 45, wherein the voids are
depressions in an upper surface of a midsole of the footwear.
48. The footwear recited in claim 45, wherein the voids are
depressions in a lower surface of a midsole of the footwear.
49. The footwear recited in claim 45, wherein the voids are
depressions in a removable sockliner of the footwear.
50. The footwear recited in claim 45, wherein at least one cover
sheet is secured to the sole and extends over the inserts.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This U.S. patent application is a continuation-in-part
application of and claims priority to U.S. patent application Ser.
No. 10/845,302, which was filed in the U.S. Patent and Trademark
Office on May 14, 2004 and entitled Footwear Sole Component With A
Single Sealed Chamber, such prior U.S. patent application being
entirely incorporated herein by reference. U.S. patent application
Ser. No. 10/845,302 is, in turn, a divisional application of U.S.
patent application Ser. No. 10/143,745, which issued as U.S. Pat.
No. 6,796,056 on Sep. 28, 2004.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an improved cushioning
system for athletic footwear which provides a large deflection for
cushioning the initial impact of footstrike, a controlled stiffness
response, a smooth transition to bottom-out and stability, and more
specifically to a system which allows for customization of these
response characteristics by adjustment of the orientation of a
single bladder or insert in a resilient foam material.
[0004] 2. Description of Related Art
[0005] Basketball, tennis, running, and aerobics are but a few of
the many popular athletic activities which produce a substantial
impact on the foot when the foot strikes the ground. To cushion the
strike force on the foot, as well as the leg and connecting
tendons, the sole of shoes designed for such activities typically
include several layers, including a resilient, shock absorbent
layer such as a midsole and a ground contacting outer sole or
outsole which provides both durability and traction.
[0006] The typical midsole uses one or more materials or components
which affect the force of impact in two important ways, i.e.,
through shock absorption and energy dissipation. Shock absorption
involves the attenuation of harmful impact forces to thereby
provide enhanced foot protection. Energy dissipation is the
dissemination of both impact and useful propulsive forces. Thus, a
midsole with high energy dissipation characteristics generally has
a relatively low resiliency and, conversely, a midsole with low
energy dissipating characteristics generally has a relatively high
resiliency. The optimum midsole should be designed with an impact
response that takes into consideration both adequate shock
absorption and sufficient resiliency.
[0007] One type of sole structure in which attempts have been made
to design appropriate impact response are soles, or inserts for
soles, that contain a bladder element of either a liquid or gaseous
fluid. These bladder elements are either encapsulated in place
during the foam midsole formation or dropped into a shallow,
straight walled cavity and cemented in place, usually with a
separate piece of foam cemented on top. Particularly successful gas
filled structures are disclosed in U.S. Pat. Nos. 4,183,156 and
4,219,945 to Marion F. Rudy, the contents of which are hereby
incorporated by reference. An inflatable bladder or barrier member
is formed of an elastomeric material having a multiplicity of
preferably intercommunicating, fluid-containing chambers inflated
to a relatively high pressure by a gas having a low diffusion rate
through the bladder. The gas is supplemented by ambient air
diffusing through the bladder to thereby increase the pressure
therein and obtain a pressure that remains at or above its initial
value over a period of years. (U.S. Pat. Nos. 4,340,626, 4,936,029
and 5,042,176 to Marion F. Rudy describe various diffusion
mechanisms and are also hereby incorporated by reference.)
[0008] The pressurized, inflatable bladder insert is incorporated
into the insole structure, in the '156 patent, by placement within
a cavity below the upper, e.g., on top of a midsole layer and
within sides of the upper or midsole. In the '945 patent, the
inflatable bladder insert is encapsulated within a yieldable foam
material, which functions as a bridging moderator filling in the
irregularities of the bladder, providing a substantially smooth and
contoured surface for supporting the foot and forming an easily
handled structure for attachment to an upper. The presence of the
moderating foam, however, detracts from the cushioning and
perception benefits of the gas inflated bladder. Thus, when the
inflated bladder is encapsulated in a foam midsole, the impact
response characteristics of the bladder are hampered by the effect
of the foam structure. Referring to FIG. 5 of the '945 patent for
example, the cross-section of the midsole shows a series of tubes
linked together to form the gas filled bladder. When the bladder is
pressurized its tendency is to be generally round in cross-section.
The spaces between those bladder portions are filled with foam.
Because the foam-filled spaces include such sharp corners, the foam
density in the midsole is uneven, i.e., the foam is of higher
density in the corners and smaller spaces, and lower density along
rounded or flatter areas of the bladder. Since foam has a stiffer
response to compression, in the tighter areas with foam
concentrations, the foam will dominate the cushioning response upon
loading. So instead of a high deflection response, the response can
be stiff due to the foam reaction. The cushioning effects of the
bladder thus may be reduced due to the uneven concentrations of
foam. In addition, the manufacturing techniques used to produce the
sole structure formed by the combination of the foam midsole and
inflated bladder must also be accommodating to both elements. For
example, when encapsulating the inflatable bladder, only foams with
relatively low processing temperatures can be used due to the
susceptibility of the bladder to deform at high temperatures. The
inflated bladder must also be designed with a thickness less than
that of the midsole layer in order to allow for the presence of the
foam encapsulating material completely therearound. Thus, there are
manufacturing as well as performance constraints imposed in the
foam encapsulation of an inflatable bladder.
[0009] A cushioning shoe sole component that includes a structure
for adjusting the impact response of the component is disclosed in
U.S. Pat. No. 4,817,304 to Mark G. Parker et al. The sole component
of Parker et al. is a viscoelastic unit formed of a gas containing
bladder and an elastomeric yieldable outer member encapsulating the
bladder. The impact resistance of the viscoelastic unit is adjusted
by forming a gap in the outer member at a predetermined area where
it is desired to have the bladder predominate the impact response.
The use of the gap provides an adjustment of the impact response,
but the adjustment is localized to the area of the gap. The '304
patent does not disclose a way of tuning the impact response to
optimize the response over the time of footstrike through the
appropriate structuring of both the bladder and encapsulating
material.
[0010] A cushioning system for a shoe sole which uses a bladder
connected only along its perimeter and supported in an opening in
resilient foam material, is disclosed in U.S. Pat. No. 5,685,090 to
Tawney et al., which is hereby incorporated by reference. The
bladder of Tawney et al. has generally curved upper and lower major
surfaces and a sidewall that extends outward from each major
surface. The angled sidewalls form a horizontally orientated
V-shape in cross-section, which fits into a correspondingly shaped
groove in the opening in the surrounding resilient foam material.
Portions of the top and bottom of the bladder are not covered with
the foam material. By forming the bladder without internal
connections between the top and bottom surfaces, and exposing
portions of the top and bottom surfaces, the feel of the bladder is
maximized. However, the '090 patent does not disclose a way of
tuning the impact response through design of both the bladder and
foam material.
[0011] One type of prior art construction concerns air bladders
employing an open-celled foam core as disclosed in U.S. Pat. Nos.
4,874,640 and 5,235,715 to Donzis. These cushioning elements do
provide latitude in their design in that the open-celled foam cores
allow for a variety of shapes of the bladder. However, bladders
with foam core tensile members have the disadvantage of unreliable
bonding of the core to the barrier layers. One of the main
disadvantages of this construction is that the foam core defines
the shape of the bladder and thus must necessarily function as a
cushioning member at footstrike which detracts from the superior
cushioning properties of air alone. The reason for this is that in
order to withstand the high inflation pressures associated with
such air bladders, the foam core must be of a high strength which
requires the use of a higher density foam. The higher the density
of the foam, the less the amount of available air space in the air
bladder. Consequently, the reduction in the amount of air in the
bladder decreases the benefits of cushioning. Cushioning generally
is improved when the cushioning component, for a given impact,
spreads the impact force over a longer period of time, resulting in
a smaller impact force being transmitted to the wearer's body.
[0012] Even if a lower density foam is used, a significant amount
of available air space is sacrificed which means that the
deflection height of the bladder is reduced due to the presence of
the foam, thus accelerating the effect of "bottoming-out."
Bottoming-out refers to the failure of a cushioning device to
adequately decelerate an impact load. Most cushioning devices used
in footwear are non-linear compression based systems, increasing in
stiffness as they are loaded. Bottom-out is the point where the
cushioning system is unable to compress any further.
Compression-set refers to the permanent compression of foam after
repeated loads which greatly diminishes its cushioning properties.
In foam core bladders, compression set occurs due to the internal
breakdown of cell walls under heavy cyclic compression loads such
as walking or running. The walls of individual cells constituting
the foam structure abrade and tear as they move against one another
and fail. The breakdown of the foam exposes the wearer to greater
shock forces, and in the extreme, to formation of an aneurysm or
bump in the bladder under the foot of the wearer, which will cause
pain to the wearer.
[0013] Another type of composite construction prior art concerns
air bladders which employ three dimensional fabric as tensile
members such as those disclosed in U.S. Pat. Nos. 4,906,502,
5,083,361 and 5,543,194 to Rudy; and U.S. Pat. Nos. 5,993,585 and
6,119,371 to Goodwin et al., which are hereby incorporated by
reference. The bladders described in the Rudy patents have enjoyed
commercial success in NIKE, Inc. brand footwear under the name
Tensile-Air.RTM.. Bladders using fabric tensile members virtually
eliminate deep peaks and valleys. In addition, the individual
tensile fibers are small and deflect easily under load so that the
fabric does not interfere with the cushioning properties of
air.
[0014] One shortcoming of these bladders is that currently there is
no known manufacturing method for making complex-curved, contoured
shaped bladders using these fabric fiber tensile members. The
bladders may have different levels, but the top and bottom surfaces
remain flat with no contours and curves.
[0015] Another disadvantage is the possibility of bottoming-out.
Although the fabric fibers easily deflect under load and are
individually quite small, the sheer number of them necessary to
maintain the shape of the bladder means that under high loads, a
significant amount of the total deflection capability of the air
bladder is reduced by the volume of fibers inside the bladder and
the bladder can bottom-out.
[0016] One of the primary problems experienced with the fabric
fibers is that these bladders are initially stiffer during initial
loading than conventional air bladders. This results in a firmer
feel at low impact loads and a stiffer "point of purchase" feel
that belies their actual cushioning ability. The reason for this is
because the fabric fibers have a relatively low elongation to
properly hold the shape of the bladder in tension, so that the
cumulative effect of thousands of these relatively inelastic fibers
is a stiff feel. The tension of the outer surface caused by the low
elongation or inelastic properties of the tensile member results in
initial greater stiffness in the air bladder until the tension in
the fibers is broken and the effect of the air in the bladder can
come into play.
[0017] Another category of prior art concerns air bladders which
are injection molded, blow-molded or vacuum-molded such as those
disclosed in U.S. Pat. No. 4,670,995 to Huang; U.S. Pat. No.
4,845,861 to Moumdjian; U.S. Pat. Nos. 6,098,313, 5,572,804, and
5,976,541 to Skaja et al.; and U.S. Pat. No. 6,029,962 to Shorten
et al. These manufacturing techniques can produce bladders of any
desired contour and shape including complex shapes. A drawback of
these air bladders can be the formation of stiff, vertically
aligned columns of elastomeric material which form interior columns
and interfere with the cushioning benefits of the air. Since these
interior columns are formed or molded in the vertical position and
within the outline of the bladder, there is significant resistance
to compression upon loading which can severely impede the
cushioning properties of the air.
[0018] Huang '995 teaches forming strong vertical columns so that
they form a substantially rectilinear cavity in cross section. This
is intended to give substantial vertical support to the air cushion
so that the vertical columns of the air cushion can substantially
support the weight of the wearer with no inflation (see '995,
Column 5, lines 4-11). Huang '995 also teaches the formation of
circular columns using blow-molding. In this prior art method, two
symmetrical rod-like protrusions of the same width, shape and
length extend from the two opposite mold halves to meet in the
middle and thus form a thin web in the center of a circular column
(see Column 4, lines 47-52, and depressions 21 in FIGS. 1-4, 10 and
17). These columns are formed of a wall thickness and dimension
sufficient to substantially support the weight of a wearer in the
uninflated condition. Further, no means are provided to cause the
columns to flex in a predetermined fashion, which would reduce
fatigue failures. Huang's columns 42 can be prone to fatigue
failure due to compression loads, which force the columns to buckle
and fold unpredictably. Under cyclic compression loads, the
buckling can lead to fatigue failure of the columns.
[0019] Prior art cushioning systems which incorporate an air bag or
bladder can be classified into two broad categories: cushioning
systems which focused on the design of the bladder and its response
characteristics; and cushioning systems which focused on the design
of the supporting mechanical structure in and around the
bladder.
[0020] The systems that focused on the air bladder itself dealt
with the cushioning properties afforded by the pneumatics of the
sealed, pressurized bladder. The pneumatic response is a desirable
one because of the large deflections upon loading which corresponds
to a softer, more cushioned feel, and a smooth transition to the
bottom-out point. Potential drawbacks of a largely pneumatic system
may include poor control of stiffness through compression and
instability. Control of stiffness refers to the fact that a solely
pneumatic system will exhibit the same stiffness function upon
loading. There is no way to control the stiffness response.
Instability refers to potential uneven loading and potential shear
stresses due to the lack of structural constraints on the bladder
upon loading.
[0021] Pneumatic systems also focused on the configuration of
chambers within the bladder and the interconnection of the chambers
to effect a desired response. Some bladders have become fairly
complex and specialized for certain activities and placements in
the midsole. The amount of variation in bladder configurations and
their placement have required stocking of dozens of different
bladders in the manufacturing process. Having to manufacture
different bladders for different models of shoes adds to cost both
in terms of manufacture and waste.
[0022] Certain prior pneumatic systems generally used air or gas in
the bladder at pressures substantially above ambient. To achieve
and maintain pressurization, it has been necessary to employ
specially designed, high-cost barrier materials to form the
bladders, and to select the appropriate gas depending on the
barrier material to minimize the migration of gas through the
barrier. This has required the use of specialty films and gases
such as nitrogen or sulfur hexafluoride at high pressures within
the bladders. Part and parcel of high pressure bladders filled with
gases other than air or nitrogen is added requirement to protect
the bladders in the design of the midsole to prevent rupture or
puncture.
[0023] The prior art systems which focused on the mechanical
structure by devising various foam shapes, columns, springs, etc.,
dealt with adjusting the properties of the foam's response to
loading. Foam provides a cushioning response to loading in which
the stiffness function can be controlled throughout and is very
stable. However, foam, even with special construction techniques,
does not provide the large deflection upon loading that pneumatic
systems can deliver.
SUMMARY OF THE INVENTION
[0024] The present invention pertains to a sole component for
footwear incorporating a sealed, fluid containing chamber and
resilient material to harness the benefits of both a pneumatic
system and a mechanical system, i.e., provide a large deflection at
high impact, controlled stiffness response, a smooth transition to
maximum deflection and stability. The sole component of the present
invention is specifically designed to optimally combine pneumatic
and mechanical structures and properties. The sealed, fluid
containing chamber can be made by sealing an appropriately shaped
void in the resilient material, or forming a bladder of resilient
barrier material.
[0025] Recognizing that resilient material, such as a foamed
elastomer, and air systems each posses advantageous properties, the
present invention focuses the design of cushioning systems
combining the desirable properties of both types, while reducing
the effect of their undesirable properties.
[0026] Foamed elastomers as a sole cushioning material possesses a
very desirable material property: progressively increasing
stiffness. When foamed elastomers are compressed the compression is
smooth as its resistance to compression is linear or progressive.
That is, as the compression load increases, foamed elastomers
become or feel increasingly stiff. The high stiffness allows the
foamed elastomers to provide a significant contribution to a
cushioning system. The undesirable properties of foamed elastomers
include limitations on deflection by foam density, quick
compression set, and limited design options.
[0027] Gas filled chambers or bladders also possess very desirable
properties such as high deflection at impact and a smooth
transition to bottom-out. The soft feel of a gas filled bladder
upon loading is the effect of high deflection, which demonstrates
the high energy capacity of a pneumatic unit. Some difficulties of
designing gas filled bladder systems include instability and the
need to control the geometry of the bladder. Pressurized bladders
by their very nature tend to take on a shape as close to a ball, or
another round cross-section, as possible. Constraining this
tendency can require complex manufacturing methods and added
elements to the sole unit.
[0028] In the past these two types of structures were used together
but were not specifically designed to work together to exhibit the
best properties of each system while eliminating or minimizing the
drawbacks.
[0029] This is now possible due to the specially designed single
chamber, pear-shaped, or taper-shaped bladder that can be used in a
variety of locations and configurations in a midsole. The tapered
shape has at least one planar major surface and a contoured
surface, which is contoured from side to side and front to back.
This contoured surface, when used with a resilient material, such
as a foamed elastomer, provides a smooth stiffness transition from
the resilient material to the bladder and vice-versa. The single
chamber tapered bladder can be used in a variety of locations and
configurations in a midsole to provide desired response
characteristics. Only one bladder shape is required to be stocked
which will significantly reduce manufacturing costs.
[0030] The present invention provides the best of pneumatic and
mechanical cushioning properties without high pressurization of the
air bladder. The air bladder used in the present invention is
simply sealed with air at ambient pressure or at a slightly
elevated pressure, within 5 psi (gauge) of ambient, and does not
require nitrogen or specialized gases. Since the bladder is
pressurized to a very low pressure if at all, the air bladder of
the present invention also does not require a special barrier
material. Any available barrier material can be used to make the
bladder, including recycled materials which presents another
substantial cost advantage over conventional pressurized bladders.
Against the prevailing norm of pressurization, the cushioning
system of the present invention is engineered to provide sufficient
cushioning with an air bladder sealed at ambient pressure.
[0031] The single chamber air bladder of the present invention can
be formed by blow-molding or vacuum forming with the bladder sealed
from ambient air at ambient pressure or at slightly elevated
pressure. Because high pressurization is not required, the
additional manufacturing steps of pressurizing and sealing a
pressurized chamber are not required. Minimizing complexity in this
way will also be less expensive resulting in a very cost-effective
system that provides all of the benefits of more expensive
specially designed pneumatic systems.
[0032] When a cushioning system is loaded, the desired response is
one of large deflection at initial load or strike to absorb the
shock of the greatest force, and a progressively increasing
stiffness response to provide stability through the load. The
overall stiffness is controlled primarily by the density or
hardness of the resilient material--the foam density or hardness
when a foamed elastomer is used. Because of the smoothly contoured
transition areas of the foam material and air bladder interface,
foam densities are even and high concentrations are eliminated. The
gentle slopes and contours of the tapered air bladder provide
gradual transitions between the foam material and air bladder
responses. Thus, because of the shape of the air bladder, the
response to a load can be controlled by its placement. Placing the
tapered, for example, pear-shaped air bladder at ambient or very
low pressure under the area of greatest force of the wearer's foot
affords greater deflection capacity than current systems, which
employ high pressurization. This is due to the relatively large
volume of the tapered air bladder, in combination with the lack of
internal connections or structure within the interior area of the
bladder, allowing for a relatively large deflection upon load. For
example, when the pear shape is used, the larger, more bulbous end
of the pear shaped bladder will deflect more than the narrower end.
With this parameter in mind, rotation and movement of the air
bladder can provide very different cushioning characteristics,
which can mimic the effect of more complex and expensive foam
structures within a midsole. In this way the air bladder and foam
material work in concert to provide the desired response.
[0033] These and other features and advantages of the invention may
be more completely understood from the following detailed
description of the preferred embodiments of the invention with
reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 is an exploded perspective view of a footwear sole in
accordance with the present invention showing air bladders placed
in the heel and metatarsal head areas.
[0035] FIG. 2A is a top plan view of the sole of FIG. 1 shown with
the air bladders positioned in the foam midsole material.
[0036] FIG. 2B is a top plan view of an alternative embodiment of
the footwear sole of FIG. 1 in which an air bladder is rotated in
its orientation to provide a specific response.
[0037] FIG. 3A is a cross-section taken along line 3A-3A of FIG.
2A.
[0038] FIG. 3B is a cross-section taken along line 3B-3B of FIG.
2B.
[0039] FIG. 4 is a cross-section taken along line 4-4 of FIG.
2A.
[0040] FIG. 5 is a side elevational view of the heel air bladder
shown in the top-load configuration.
[0041] FIG. 6 is an end elevation view of the air bladder of FIG.
5.
[0042] FIG. 7 is a bottom plan view of the air bladder of FIG.
5.
[0043] FIG. 8A is a cross-section taken along line 8-8 of FIG.
7.
[0044] FIG. 8B is a cross-section similar to that of FIG. 8A and
shown with a representation of midsole foam material to illustrate
the smooth transition of stiffness during footstrike.
[0045] FIG. 9A is a cross-section taken along line 9-9 of FIG.
7.
[0046] FIG. 9B is a cross-section similar to that of FIG. 9A and
shown with a representation of midsole foam material to illustrate
the smooth transition of stiffness during footstrike.
[0047] FIG. 10 is a side elevational view of the calcaneus air
bladder shown in the top-load configuration.
[0048] FIG. 11 is an end elevation view of the air bladder of FIG.
10.
[0049] FIG. 12 is a bottom plan view of the air bladder of FIG.
10.
[0050] FIG. 13 is a cross-section taken along line 13-13 of FIG.
12.
[0051] FIG. 14 is a cross-section taken along line 14-14 of FIG.
12.
[0052] FIG. 15 is an exploded assembly view of the cushioning
system shown in FIG. 1 with other elements of a shoe assembly.
[0053] FIG. 16A is an exploded perspective view of another
embodiment of a heel chamber in accordance with the present
invention.
[0054] FIG. 16B is a cross-section taking along line 16B-16B of
FIG. 16A, with the heel chamber sealed.
[0055] FIG. 16C is a cross-section taken along line 16C-16C of FIG.
16A, with the heel chamber sealed.
[0056] FIG. 17A is a diagrammatic cross-section of a sealed chamber
illustrating film tensioning and internal pressure when no force is
applied to the sealed chamber.
[0057] FIG. 17B is a diagrammatic cross-section of a sealed chamber
illustrating film tensioning and internal pressure when light force
is applied to the sealed chamber.
[0058] FIG. 17C is a diagrammatic cross-section of a sealed chamber
illustrating film tensioning and internal pressure when increasing
force is applied to the sealed chamber.
[0059] FIG. 17D is a diagrammatic cross-section of a sealed chamber
illustrating film tensioning and internal pressure when high force
is applied to the sealed chamber.
[0060] FIG. 18 is an exploded perspective view of another footwear
sole in accordance with the present invention.
[0061] FIG. 19 is a top plan view of the sole of FIG. 1.
[0062] FIG. 20A is a cross-section taken along line 20A-20A of FIG.
19.
[0063] FIG. 20B is a cross-section taken along line 20B-20B of FIG.
19.
[0064] FIG. 21 is a top plan view of another footwear sole
configuration.
[0065] FIG. 22A is a cross-section taken along line 22A-22A of FIG.
21.
[0066] FIG. 22B is a cross-section taken along line 22B-22B of FIG.
21.
[0067] FIG. 23 is a top plan view of yet another footwear sole
configuration
[0068] FIG. 24 is a cross-section taken along line 24-24 of FIG.
23.
[0069] FIG. 25 is a cross-section of an article of footwear
receiving a sockliner in accordance with the present invention.
[0070] FIG. 26 is a perspective view of a sockliner.
[0071] FIG. 27 is a side elevational view of the sockliner.
DETAILED DESCRIPTION OF THE INVENTION
[0072] Sole 10 of the present invention includes a midsole 12 of an
elastomer material, preferably a resilient foam material and one or
more air bladders 14, 16 disposed in the midsole. FIGS. 1-4
illustrate a cushioning system with a bladder 14 disposed in the
heel region and a bladder 16 disposed in the metatarsal head
region, the areas of highest load during footstrike. The bladders
are used to form sealed chambers of a specific shape. In an
alternate embodiment a sealed chamber can be formed from a void in
an elastomeric chamber that is sealed with a separate cover
material. The shape of the chambers and their arrangement in the
elastomeric material, particularly in the heel region, produces the
desired cushioning characteristics of large deflection for shock
absorption at initial footstrike, then progressively increasing
stiffness through the footstrike.
[0073] The preferred shape of the bladder is a contoured taper
shaped outline, preferably pear-shaped, as best seen in FIGS. 5-14.
This shape was determined by evaluating pressures exerted by the
bottom of a wearer's foot. The shape of the air bladder matches the
pressure map of the foot, wherein the higher the pressure, the
higher the air-to-foam depth ratio. The shape of the outline is
defined by the two substantially planar major surfaces in
opposition to one another and in generally parallel relation: a
first major surface 18 and a second major surface 20. These
surfaces each have a perimeter border 22, 24 respectively which
define the shape of the bladder so that bladder 14 has a larger
rounded end 27 and tapers to a more pointed narrow end 29. Narrow
end 29 has a width substantially less than the maximum width of
larger rounded end 27 so that major surfaces 18 and 20 take on a
generally pear-shaped outline. Second major surface 20 has
substantially the same outline as first major surface 18 but is
smaller in surface area by approximately 50%. At the rounded end 27
of the bladder, first major surface 18 and second major surface 20
are only slightly offset as seen in FIGS. 7-8. At narrow end 29 of
the bladder, the point of second major surface 20 is further apart
from the corresponding point of first major surface 18 than at the
rounded end. First major surface 18 and second major surface 20 are
symmetric about a longitudinal center line 31 of the bladder. These
major surfaces are connected together by a contoured sidewall 26,
which extends around the entire bladder. Sidewall 26 is preferably
integral with first major surface 18 and second major surface 20,
and if the bladder is formed of flat sheets, i.e., vacuum molded, a
substantial portion of sidewall 26 is formed from the same sheet
making up second major surface 20. Even in a blow-molded bladder,
the seam is located such that the sidewall appears to be formed on
the same side of the seam as the second major surface.
[0074] As best seen in FIGS. 7, 8A and 9A, the longitudinal spacing
between the rounded end of second major surface 20 and the rounded
end of first major surface 18 is less than the longitudinal spacing
between the pointed end of second major surface 20 and the pointed
end of first major surface 18. This distance is covered in a
contoured manner by sidewall 26 as best seen in FIGS. 5-9A so as to
provide a long, smoothly sloped contour at the pointed end of the
bladder and a shorter, smoothly sloped contour at the rounded end.
This results in a bladder that has a substantially flat side where
major surface 18 is disposed, and a substantially convex side where
major surface 20 is disposed. Bladder 14 has one axis of symmetry,
i.e., the longitudinal axis, and is asymmetrical in all other
aspects. This seemingly simple, articulated shape of the air
bladder provides a multitude of possible variations depending on
the desired cushioning response to load. Also as seen in the
Figures, the major surfaces are connected to one another only by
the sidewalls. The major surfaces are devoid of any internal
connections.
[0075] As seen in FIGS. 1, 2A-B and 3A-B, the orientation of the
bladder in the foam material can be varied to attain differing
cushioning properties. Air bladder 14 can be oriented in the
resilient foam material with its longitudinal axis generally
aligned with the longitudinal axis of the midsole as shown in FIG.
2A, which will provide overall cushioning and lateral support for a
wide range of wearers. Alternatively, air bladder 14 can be
oriented with its longitudinal axis rotated with respect to the
longitudinal axis, toward the lateral side, of the midsole as shown
in FIG. 2B. With the bladder rotated in this manner, more foam
material is present in the medial side of the midsole thereby
creating a simulated medial post since the foam material will
dominate the response to a load in the medial portion and thereby
feel stiffer than the response in the lateral side which will be
dominated by the air bladder's deflection. More support is provided
on the medial side to stabilize the medial side of the sole and
inhibit over-pronation during footstrike. By adjusting the
orientation of the air bladder in this manner, the response
characteristics of the cushioning system can be customized. The
orientations shown in FIGS. 2A and 2B are intended to be exemplary,
and other orientations are contemplated to be within the scope of
the invention.
[0076] Another possible adjustment to the air bladder's orientation
is the determination of which side of the air bladder faces upward.
When bladder 14 is positioned in resilient foam material 12 in the
orientation shown in FIGS. 1 and 3A, the convex side of the bladder
is cradled in the foam, and the flat side faces upward and is not
covered with foam, thereby providing more cushioning, i.e. greater
deflection of the bladder, and a smooth transition from the feel of
the bladder to the stiffer feel of the foam upon loading. The
orientation of FIG. 3A in which the mostly planar surface of the
bladder is loaded, is referred to herein as the top loaded
condition.
[0077] It is possible to turn bladder 14 over and orient it in the
foam so that the substantially flat side, containing major surface
18, faces downward and the convex side, containing major surface
20, faces upward, FIG. 3B, so that a foam material arch above the
bladder takes the load. This orientation is referred to herein as
the bottom loaded condition in which a layer of foam material is
disposed over the convex side of the bladder. The bottom loaded
condition provides a stiffer response than the top loaded condition
since more foam material is present between the heel and the
bladder to moderate the feel of the bladder's deflection.
Additionally, a structural arch is formed. This results in a
stronger support for the heel region during footstrike.
[0078] Similarly, air bladder 16 which is illustrated to be in the
metatarsal head region of the midsole affords different cushioning
properties depending on its orientation. Air bladder 16 also has a
first major surface 28, which is generally planar, and a second
major surface 30, which is also generally planar and is smaller in
surface area than first surface 28. The second surface has a
surface area approximately 25% to 40% of the surface area of the
first surface. These surfaces are generally parallel to one another
and are defined by first perimeter border 32 and second perimeter
border 34 which are connected by a sidewall 36, similar to sidewall
26 of air bladder 14. Because of the relatively small size of
second surface 30, sidewall 36 has a relatively flat slope, in
other words, when placed in resilient foam material the transition
from air bladder to foam response is very gradual with air bladder
16.
[0079] Air bladder 16 is shown placed in the resilient foam midsole
in a top loaded configuration, but as with air bladder 14, it could
be turned over to provide a different response to load. The
orientation of air bladder 16 with its longitudinal axis aligned
with the direction of the metatarsal heads of a wearer as shown in
FIG. 2A will provide the desired cushioning response for a wide
variety of wearers. However, the orientation can be rotated as
explained above to achieve customized responses.
[0080] The line FS in FIG. 2A, which will be referred to as
footstrike line FS, illustrates the line of maximum pressure
applied by the foot of a wearer to a shoe sole during running by a
person whose running style begins with footstrike in the lateral
heel area (rear foot strikers). The line FS is a straight line
generalization of the direction that the line of maximum pressure
follows for rearfoot strikers. The actual line of pressure for a
given footstrike would not be precisely along straight line FS, but
would generally follow line FS. As seen in this Figure, footstrike
line FS starts in the lateral heel area, proceeds diagonally
forward and towards the medial side as it proceeds through the heel
area (pronation), turns in a more forward direction through the
forward heel and arch areas, and finally proceeds through the
metatarsal, metatarsal head and toe areas, with the foot leaving
the ground (toe off) adjacent the area of the second metatarsal
head.
[0081] FIGS. 8B and 9B illustrate how the midsole foam material and
the shape of bladder 14 accomplishes smooth transition of stiffness
as the foot of the wearer proceeds through footstrike in the heel
area towards the forefoot. At initial footstrike, the foot contacts
the rear lateral heel area where the midsole is formed entirely of
foam material (F1) to provide a firm, stable, yet shock-absorbing
effect. As footstrike proceeds medially and forwardly, the amount
of foam material (F2) underlying the foot gradually decreases and
the thickness of bladder 14 gradually increases because of the
smooth, sloped contour of sidewall 26 in the medial side area
(BSM). In this area, the effect of the more compliant bladder 14
gradually takes greater effect for shock absorbing and gradually
decreasing the stiffness of the midsole, until an area of maximum
bladder thickness and minimum foam thickness (F3) is reached. The
maximum bladder thickness occurs in the side-to-side center area
(BC) of bladder 14, which underlies the calcaneus of the foot. In
this manner, maximum deflection of bladder 14, minimum stiffness
and maximum shock attenuation is provided under the calcaneus.
[0082] As footstrike proceeds medially past center area BC,
sidewall 26 has a smooth contour that decreases the thickness of
bladder 14 in the lateral side area (BSL) of the bladder so that
the thickness of the foam (F4) gradually increases to again provide
a smooth transition from the more compliant effect of bladder 14 to
the more stiff, supportive effect of the foam material. When
footstrike reaches the medial side of the front heel area, the full
thickness of foam F5 is reached to provide the maximum supportive
effect of the foam material. As seen by comparing FIG. 2A to FIG.
2B, the supportive effect of the foam material in the medial heel
front area can be maximized by angling the front bladder 14 toward
the lateral side as shown in FIG. 2B. Such angling places more foam
material, as compared to bladder 14 in FIG. 2A, in the medial front
heel area. This orientation is preferred for a shoe designed to
restrict over-pronation during running.
[0083] A smooth transition from the effect of the bladder to the
effect of the foam material also occurs as footstrike proceeds
forward from the rear heel area toward the forefoot area. This
transition is accomplished in a similar manner to the transition
from the medial to lateral direction by smoothly sloping the
forward sidewall of bladder 14 in the forward bladder area BF, and
by reducing the overall width of bladder 14 as it extends from its
larger rounded end 27 to its more pointed narrow end 29. In this
manner, the thickness of bladder 14 gradually decreases and the
thickness of the foam material F6 gradually increases until the
full thickness of the foam material is reached in front of bladder
14.
[0084] An alternative method of making the cushioning component is
to mold the resilient material, such as a foam elastomer, with a
void in the shape of the taper shaped bladder and sealing off the
void to form a sealed chamber. Any conventional molding technique
can be used, such as injection molding, pour molding, or
compression molding. Any moldable thermoplastic elastomer can be
used, such as ethylene vinyl acetate (EVA) or polyurethane (PU).
This alternative method, as well as an alternative configuration
for the sealed chamber within the foam material is illustrated in
FIGS. 16A, 16B, and 16C. When a foam elastomer is molded with an
insert to provide the void, the foam surrounding the insert will
flow and form a skin during the molding process. At the conclusion
of the molding process the insert is removed, and the opening which
allowed removal of the insert is sealed, such as by the attachment
of the outsole, a lasting board, or another piece of resilient
material, such as a sheet of thermoplastic urethane 19, as
illustrated in FIGS. 16A-C. The skin formed from the molding
process acts like air bladder material and seals the air in the
void, without the need for a separate air bladder. If a closed cell
foam material is used, skin formation would not be required. The
sealed chamber provides a comparable cushioning effect as having an
ambient air filled air bladder surrounded by the foam. This
manufacturing method is economical as no air bladder materials are
required. Also, the step of forming the separate air bladder is
eliminated.
[0085] As seen in FIGS. 16A to 16C, an alternate sealed chamber 14'
is configured for use in the heel area of sole 10'. As with bladder
14, sealed chamber 14' has a contoured tapered shape, and is
orientated in the heel area to match with the pressure map of the
foot, wherein the higher the pressure, the higher the air to foam
depth ratio. Sealed chamber 14' has two substantially planar major
surfaces in opposition to one another and in a generally parallel
relation: a first major surface 18' and a second major surface 20'.
These surfaces each have a perimeter border 22', 24', respectively,
which define the shape of the bladder so that bladder 14 has a
first rounded end 27' and tapers slightly to a flat end 29'. A
contoured sidewall 26' connects the major surfaces between their
respective perimeters 22' and 24'.
[0086] Sealed chamber 14' accomplishes smooth stiffness transition
from the lateral to medial direction, and from the rear to forward
direction in a manner similar to bladder 14. Comparing FIGS. 9B and
16C, it is seen that a slope contour from bottom surface 24' and
along sidewalls 26' is similar on both the medial and lateral sides
of sealed chamber 14' as with bladder 14. Thus, proceeding from
heel strike in the lateral rear area and moving towards the medial
rear area, the smooth transition of stiffness described above is
accomplished. Since the perimeter borders 22' and 24' do not taper
inwardly as much as the perimeter borders of bladder 14, smooth
stiffness transition proceeding from the rear of sealed chamber 14'
forward is accomplished by varying the slope from bottom surface
20' forward along sidewall 26' in a manner different from bladder
14. As seen in FIG. 16B, the bottom of sealed chamber 14' tapers
upwardly at a greater rate in the forward direction, from bottom
surface 20' through sidewall 26' than the upward taper of the
bottom in bladder 14, as seen in FIG. 8B. The more rapid upward
taper compensates for the lack of narrowing of sealed chamber 14',
so as to increase the amount of foam material underlying the
bladder as foot strike moves in the forward direction in a proper
gradual rate.
[0087] Stiffness can be controlled by adjusting the orientation of
the air bladders. For instance, placing the air bladders directly
under the calcaneus in the top loaded orientation results in less
initial stiffness during footstrike and more later stiffness than
when the bladder is placed under the calcaneus in the bottom loaded
orientation with foam between the calcaneus and the bladder.
Overall stiffness response is controlled primarily by material
density or hardness. For the top loaded configuration, increasing
foam density or hardness increases the latter stiffness. For the
bottom load condition, increasing foam density or hardness
increases the middle and latter stiffness. The stiffness slope is
also determined by volume, with large air bladders having lower
stiffness and therefore more displacement upon loading. This is due
to the larger air volume in a single chamber allowing a gradual
pressure increase as the bladder volume decreases during
compression. Overall stiffness can also be adjusted by varying the
size of the larger first major surface 18, 18'. As will be
discussed later, as pressure is applied to the bladder or sealed
chamber, the exposed major surface 18, 18' undergoes tensioning. If
the area of the major surface 18, 18' is increased, the amount of
tension the surface undergoes decreases so that stiffness also
decreases.
[0088] A preferred foam material to use is a conventional PU foam
with a specific gravity or density in the range of 0.32 to 0.40
grams/cm.sup.3, preferably 0.36 grams/cm.sup.3. Another preferred
foam material is conventional EVA with a hardness in the range of
52 to 60 Asker C, preferably 55 Asker C. Alternatively, a solid
elastomer, such as urethane or the like, could be used if the solid
elastomer is compliant or shaped to be compliant. Another material
property relevant to the sole construction is the tensile stress at
a given elongation of the elastomeric material (modulus). A
preferred range of tensile stress at 50% elongation is between 250
and 1350 psi.
[0089] When bladder 14, or sealed chamber 14', is incorporated in
the heel area of a midsole an appropriate amount of shock
attenuation is provided when the open internal volume of the
chamber is between about 10 cubic centimeters and 65 cubic
centimeters. For such bladders, the substantially flat major
surfaces 18, 18' could be in the range of about 1,200 mm.sup.2 to
4,165 mm.sup.2. For example, when a bladder with a volume of 36
cubic centimeters is used, the pressure ranges from ambient 0 psi
to 35 psi when bladder 14 is compressed to 95% of its original
volume.
[0090] Another advantage of the sole structure of the present
invention is the manner in which bladder 14 accomplishes smooth,
progressive stiffening by the combination of film tensioning and
pressure ramping. Enhanced shock attenuation is also accomplished
by minimizing the structure under the areas of greatest pressure to
allow for greater maximum deflection while the bag is progressively
stiffening. FIGS. 17A through 17D illustrate the film tensioning
and pressure ramping in the chamber devoid of internal
connections.
[0091] FIG. 17A diagrammatically illustrates bladder or sealed
chamber 14 within an elastomeric material 13. Bladder 14 has a flat
primary surface 18 and a secondary major surface 20 with its
tapered sides. In FIG. 17A, no pressure is applied to the bladder
and the tension T.sub.0 along primary surface 18 is zero. The
pressure inside the bladder likewise is ambient and for ease of
reference will be indicated as P.sub.0 being zero.
[0092] FIG. 17B diagrammatically illustrates a small amount of
force being applied to bladder 16. For example, a person standing
at rest and an external force F.sub.1 representing the external
force applied by a calcaneus of the heel to bladder 14. As seen in
this FIG. 17B, force F.sub.1 causes primary surface 18 to bend
downward a certain degree, reducing the volume within bladder 14,
and thereby increasing the pressure to a pressure P.sub.1. The
bowing of primary surface 18 also causes tension in primary surface
18 to increase to T.sub.1. While not illustrated in these diagrams,
material 13 also compresses when forces F-F.sub.3 are applied. The
combination of increasing pressure within bladder 16 and the
compression of the foam material 13 by the downward force helps to
stabilize the foam material walls.
[0093] FIG. 17C diagrammatically illustrates increasing calcaneal
force F.sub.2 being applied to bladder 16, for example during
walking. As seen therein, the volume of bladder 16 has been reduced
further, thereby increasing the pressure within the bladder to
P.sub.2 and the tension along primary surface 18 to T.sub.2.
[0094] FIG. 17D illustrates maximum calcaneal force F.sub.3 being
applied to bladder 16, for example during running. As seen therein,
the volume of bladder 16 has been reduced substantially, thereby
substantially increasing the pressure within the bladder to P.sub.3
and the tension along primary surface 18 to T.sub.3. Since the
interior area of the bladder is devoid of internal connection
filled with foam, the bladder can compress a significant degree, as
seen in FIG. 17D, thereby enhancing the ability of the bladder to
absorb shock. While undergoing this deflection, the pressure is
ramping up, such as from P.sub.0 (ambient) to P.sub.3 (greater than
30 psi). The increase in pressure in the bladder, together with the
increasing stiffness of the foam material along the sides of the
bladder, help stabilize the footbed. The desired objective of
maximum deflection for shock absorption, in combination with medial
to lateral stability is thus attained with the combination of the
appropriately shaped bladder at ambient pressure within an
elastomeric material.
[0095] Both air bladders 14 and 16, and sealed chamber 14' contain
ambient air and are configured to be sealed at ambient pressure or
slightly elevated pressure, within 5 psi (gauge) of ambient
pressure. The low or no pressurization provides sufficient
cushioning for even repeated, cyclic loads. Because high
pressurization is not required, air bladders 14 and 16 are not
material dependent, and correspondingly, there is no requirement
for the use of specialized gases such as nitrogen or sulfur
hexafluoride, or specialized barrier materials to form the
bladders. Avoiding these specialized materials results in
significant cost savings as well as economies of manufacture.
[0096] By varying the orientation and placement of the pear-shaped
or taper shaped air bladders sealed at ambient pressure or within 5
psi of ambient pressure, it has been found that a variety of
customized cushioning responses are attainable.
[0097] The preferred methods of manufacturing the bladders are
blow-molding and vacuum forming. Blow-molding is a well-known
technique, which is well suited to economically produce large
quantities of consistent articles. The tube of elastomeric material
is placed in a mold and air is provided through the column to push
the material against the mold. Blow-molding produces clean,
cosmetically appealing articles with small inconspicuous seams.
Many other prior art bladder manufacturing methods require multiple
manufacturing steps, components and materials which makes them
difficult and costly to produce. Some prior art methods form
conspicuously large seams around their perimeters, which can be
cosmetically unappealing. Vacuum forming is analogous to
blow-molding in that material, preferably in sheet form, is placed
into the mold to take the shape of the mold, however, in addition
to introducing air into the mold, air is evacuated out to pull the
barrier material to the sides of the mold. Vacuum forming can be
done with flat sheets of barrier material which can be more cost
effective than obtaining bars, tubes or columns of material
typically used in blow molding elastomeric. A conventional
thermoplastic urethane can be used to form the bladder. Other
suitable materials are thermoplastic elastomers, polyester
polyurethane, polyether polyurethane, and the like. Other suitable
materials are identified in the '156 and '945 patents.
[0098] The cushioning components of the present invention are shown
as they would be assembled in a shoe S in FIG. 15. Cushioning
system 10 is generally placed between a liner 38, which is attached
to a shoe upper 40, and an outsole 42, which is the ground engaging
portion of the shoe.
[0099] The above discussion discloses the concept of fluid-filled
chambers of a specific shape that are located in a footwear sole.
The chambers may exhibit the configuration of sealed bladders, as
depicted in FIGS. 1-15, or the chambers may be voids within the
sole, as depicted in FIGS. 16A-16C. In another embodiment of
aspects relating to the present invention, the sole may also
incorporate a polymer foam material or other material having the
shape of the chambers disclosed in FIGS. 1-16C.
[0100] With reference to FIGS. 18-20B, a sole 10'' is depicted as
having a midsole 12'' formed from a conventional polymer foam
material, such as polyurethane or ethylvinylacetate. Midsole 12''
defines two voids 14'' in an upper surface that each receive one of
a pair of inserts 16''. The shape of inserts 16'' and their
arrangement in the material of midsole 12'', particularly in the
heel region, produces the desired cushioning characteristics of
large deflection for shock absorption at initial footstrike, then
progressively increasing stiffness through the footstrike.
Accordingly, inserts 16'' provide advantages that are similar to
bladders 14 and 16, for example.
[0101] A suitable shape for inserts 16'' is a contoured taper
shaped outline, preferably pear-shaped, that is substantially
similar in shape to bladders 14 and 16. Accordingly, the shape of
inserts 16'' is defined by the two substantially planar major
surfaces in opposition to one another and in generally parallel
relation: a first major surface 18'' and a second major surface
20'' that each have a larger rounded end that tapers to a more
pointed and narrow end. The narrow end has a width less than the
maximum width of the larger rounded end so that major surfaces 18''
and 20'' take on a generally pear-shaped outline. Second major
surface 20'' has substantially the same outline as first major
surface 18'', but is smaller in surface area by approximately 50%.
First major surface 18'' and second major surface 20'' are
symmetric about a longitudinal center line of each of inserts 16'',
but are otherwise asymmetric. Major surfaces 18'' and 20'' are
connected together by a contoured sidewall 26''.
[0102] Inserts 16'' may be formed from a variety of materials,
including polymer foam materials with a compressibility that
differs from the compressibility of midsole 12''. In some
embodiments, inserts 16'' are more compressible than midsole 12''
and compress in a manner that is similar to the compression
characteristics of bladders 14 and 16. In other embodiments,
however, inserts 16'' may be less compressible than midsole 12''.
Accordingly, the density of the foam material forming inserts 16''
may vary from the density of midsole 12''. Although each of inserts
16'' are discussed as being formed from a single foam material,
inserts 16'' may also be formed from a dual-density foam to vary
the properties of inserts 16'' in different areas. Accordingly,
portions of inserts 16'' adjacent to the larger rounded end, for
example, may be formed from a more compressible foam than the
portions of inserts 16'' that are adjacent to the narrow end.
Alternately, upper and lower portions of inserts 16'', or left and
right sides of inserts 16'', may be formed from foam materials with
different densities. In addition to foam, inserts 16'' may be
formed from a variety of other materials.
[0103] The locations and orientations of inserts 16'' may vary
significantly. With reference to FIG. 19, one of inserts 16'' is
positioned in a heel region of sole 10'' and in a location that
corresponds with a calcaneus bone of the foot. In addition, this
insert 16'' is oriented to extend in a direction of the
longitudinal length of sole 10''. Another of inserts 16'' is
positioned in a forefoot region of sole 10'' and in a location that
corresponds with the joints between the phalanges and metatarsals.
The larger rounded end of this insert 16'' is positioned adjacent a
medial side of sole 10'' to extend under the joint associated with
the hallux (i.e., the big toe), and this insert 16'' is oriented to
extend in a medial-lateral direction.
[0104] The locations and orientations of inserts 16'', as depicted
in FIG. 21, vary from the configuration discussed above. More
particularly, three inserts 16'' are positioned in sole 10''. One
of inserts 16'' is positioned in the heel region and underlies the
calcaneus, but is rotated approximately 45 degrees relative to the
longitudinal length of sole 10''. A pair of inserts 16'' are also
located in the forefoot region and are oriented to be orthogonal to
each other. Accordingly, the number of inserts 16'' may vary in
addition to the locations and orientations of inserts 16''.
[0105] A further difference between the configuration depicted in
FIGS. 18-20B and the configuration of FIGS. 21-22B is that a pair
of cover sheets 22'' are secured to midsole 12'' and extend over
inserts 16''. One of cover sheets 22'' is positioned in the heel
region and a separate cover sheet 22'' is positioned in the
forefoot region. Whereas the cover sheet 22'' in the heel region
extends over only one of inserts 16'', the cover sheet 22'' in the
forefoot region extends over two of inserts 16''. In some
embodiments, cover sheets 22'' may be bonded or otherwise secured
to first major surface 18'' in addition to a surface of midsole
12''. In other embodiments, however, cover sheets 22'' may be
unattached to first major surface 18''. Suitable materials for
cover sheets 22'' include a variety of polymer sheet materials,
such as polyurethane, but may also be various textiles, for
example. In some embodiments, one or more of inserts 16'' are
oriented within midsole 12'' such that applying a compressive force
to midsole 12'' induces a tension force in cover sheets 22'' and
also compresses inserts 16''. The compression of one of inserts
16'' induces an outward force on at least one of second major
surfaces 20'' and the sidewall surfaces of inserts 16''.
[0106] Inserts 16'', as depicted in FIGS. 18-22B, are positioned
such that first major surfaces 18'' are generally flush with the
upper surface of midsole 12''. Referring to FIGS. 23 and 24,
however, inserts 16'' are incorporated into sole 10'' such that
first major surfaces 18'' correspond with the lower surface of
midsole 12''. In other embodiments, inserts 16'' may be entirely
encapsulated within midsole 12'' such that inserts 16'' are between
each of the upper and lower surfaces of midsole 12''. Accordingly,
the vertical position of inserts 16'' may vary significantly within
the scope of the present invention.
[0107] In addition to incorporating inserts 16'' into midsole 12'',
inserts 16'' may also be incorporated into other portions of
footwear soles. With reference to FIG. 25, an article of footwear
30'' is depicted as including an upper 32'' and a sole 34''. In
addition, footwear 30'' includes a removable sockliner 36'' for
supporting the foot that is positioned adjacent to sole 34'' and
within a lower area of a void formed by upper 32''. Sockliner 36''
is depicted individually in FIGS. 26 and 27 (i.e., as removed from
footwear 30'') and may be primarily formed from a polymer foam
material. In addition, sockliner 36'' incorporates an insert 16''.
Whereas inserts 16'' of the prior embodiments may be separated from
the foot by textile layers and an insole when incorporated into
midsole 12'', insert 16'' is immediately adjacent the foot when
incorporated into sockliner 36''. In further embodiments, one or
more inserts 16'' may be incorporated into a lower area of
sockliner 36'', or various inserts 16'' may be replaced by one or
more of bladders 14 and 16.
[0108] From the foregoing detailed description, it will be evident
that there are a number of changes, adaptations, and modifications
of the present invention that come within the province of those
skilled in the art. However, it is intended that all such
variations not departing from the spirit of the invention be
considered as within the scope thereof as limited solely by the
claims appended hereto.
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